1. Technical Field
The present invention generally relates to a fire control valve and more particularly to a valve installed in a flow line for a flammable fluid or gas and which is in a normally open position to allow flow of the fluid or gas but will be automatically closed to interrupt such flow in the event of a hazardous condition, such as a fire or undue increased heat.
2. Background Information
Fire control valves, which allow flow of fluid or gas, but will be automatically closed to interrupt such flow in the event of fire or undue increased heat, are known in the prior art. Such prior art includes U.S. Pat. Nos. 4,890,635 (1990) and 5,004,003 (1991), both of which have issued in my name; and U.S. Pat. Nos. 422,583 (1890), 2,638,106 (1953), 3,473,544 (1959), 3,720,220 (1973), and 3,835,875 (1974).
Each of the patents indicated above discloses the use of a low melting metal alloy or fusible material, which when subjected to undue heat, melts and enables the triggering of mechanism connected to the fusible or low melting material to interrupt the flow of flammable fluid or gas. In some instances, the low melting material is in the form of a mechanical link, such as shown at 64 in FIG. 3 of my U S. Pat. No. 4,890,635, and at 74 in FIG. 3 of my U.S. Pat. No. 5,004,003. In U.S. Pat. No. 2,638,106, a fusible link is shown at 35 in FIG. 1 (the rupture of such link and the consequent closing of a valve being shown in FIG. 2).
My invention provides a fire control valve, which has a readily replaceable locking pin assembly for locking a movable valve member in the fire control valve in an open position to enable flow of flammable material through the fire control valve. The locking pin assembly includes as part of the assembly a heat-meltable material. When the heat-meltable material is caused by fire or undue increased heat to melt, the locking pin of the locking pin assembly is caused to retract from the valve member and allow the valve member to close, thereby interrupting the flow of flammable material through the fire control valve.
When the conditions causing the fire or undue increased heat have been corrected, it then becomes necessary to reset the fire control valve so that the flow of flammable material through the fire control valve can be resumed. The locking pin assembly is removed from the fire control valve,,and another one, which has already been prepared to include heat-meltable material, is readily installed in place of the other without undue delay, and then the valve member is locked in the open position again.
The Nielsen, Jr. patent, U.S. Pat. No. 3,473,544 (1969), discloses a plug 19, which contains a metallic alloy that will melt at a low temperature, and appears to be replaceable, but does not contain a locking pin that makes direct locking engagement with a valve member as I disclose. This is also true in the Morse patent, U.S. Pat. No. 3,835,875 (1974), which discloses a plug 20 that also contains a heat-meltable metallic alloy.
The Shiels patent, U.S. Pat. No. 2,638,106 (1953), discloses a locking pin for making direct locking engagement with a valve member, but the fuse element 35 is not part of the locking pin. Also, the valve housing must be partially dismantled before the fuse element can be replaced and the valve member reset in the open position. Shiels further discloses a diaphragm 27, which is used to seal off one end of the opening in which the locking pin is located, as well as levers 25 and 32, all of which must intervene between the fuse element 35 and the locking pin or plunger 10.
The McMath patent, U.S. Pat. No. 3,720,220 (1973), discloses a fusible plug assembly 40. When the fusible plug members 44, 46 are caused to melt, the retraction of the pin 48 in the fusible plug assembly is controlled by the movement of the valve or ball 32 against the pin 48 and the flow pressure of the liquid against the ball 32. The retraction of the locking pin in my invention is controlled solely by the locking pin assembly, once the fusible material in the locking pin assembly is caused to melt. It would also appear that the retraction movement of the pin 48 in McMath would not be as readily responsive as is the retraction movement in my invention because the patentee discloses the use of a seal 50 that necessarily must fit tightly around the pin 48 so as to prevent leakage into the fusible plug assembly of the liquid paint flowing through the valve. This tight fit would appear to cause undue friction on the pin and thereby serve to retard its retraction movement. Still a further difference in my invention over the McMath structure is that I locate the locking pin assembly on the fire control valve out of the path of flow of the flammable material and then seal off the locking pin assembly from any escape therepast of the flammable material to atmosphere.
It should be noted that in the Shiels patent mentioned above, the locking pin is also located within the flow path of the flammable material. This is also true in the Nielsen, Jr. and Morse patented structures discussed above.
The Finch et al patent, U.S. Pat. No. 422,583 (1890), discloses a locking pin G and a fusible nut I, but the fusible nut I is not interconnected with the locking pin G. Therefore, the locking pin G must be retracted from its locking with the valve-stem D after the fusible nut has been installed or else the valve-stem will not close when the fusible nut is caused to melt.